The Overall goal of this Core is to support individual projects and overall objectives by identifying and recruiting patients for participation in Program Project Studies, by collecting gastrointestinal cancer tissues from cases that arise in a population of approximately 400,000 enrollees, and by enhancing the ability of Program Project investigators to conduct longitudinal studies in colon and pancreas cancer. Through the Center for Health Studies, the GHC Population Core will facilitate access to a health care delivery system that has distinct advantages as a setting for translational research that include a large defined patient population and a rich array of information systems; established programs in cancer screening with linkage to risk factors and pathologic outcomes; and experience in the design, conduct, and analysis of intervention and observational studies of cancer prevention, control and treatment. The specific aims of the GHC Population Core are: 1) To identify and collect specimens from patients with chronic pancreatitis, pancreatic cancer, and colon cancer for proposed projects 1 and 4; 2) To recruit patients undergoing colonoscopy and collect risk factor data, fecal and blood samples, and biopsy results, and tissue specimens for longitudinal studies of colon cancer risk and development; and 4) To establish a surveillance system to monitor changes in gastrointestinal cancer incidence, morbidity, and mortality in our defined population. The GHC Population Core will build and maintain a retrospective registry with linked pathology results of more than 9800 patients who underwent colonoscopy between 1991 and 1996 and will add risk factor data for the anticipated 4800 patients who will be colonoscopied during the project period. Group Health Cooperative (GHC) is a staff-model managed care organization that serves over 400,000 enrollees in the western Washington Puget Sound region. The GHC Population Core will operate within the GHC Center for Health Studies, a research organization dedicated to the conduct of studies that contribute to scientific knowledge in the public domain and to the quality of health care at GHC.